Simultaneously Imaging Physical and Biochemical Properties of Brain Tissue
A new imaging capability maps brain metabolites and tissue magnetic susceptibility in a single scan.
Doctors may soon be able to accomplish with one brain scan what used to require two, drastically reducing the time patients must spend in a scanner, according to new research. One of the imaging techniques employed by the new scans is quantitative susceptibility mapping, known as QSM. It has been widely used in recent years for mapping tissue magnetic susceptibility—a biomarker useful for a variety of clinical applications such as detecting intracranial hemorrhages. Magnetic susceptibility is a physical property related to the amount of magnetization induced in a material when it is placed in an external magnetic field, such as that of a magnetic resonance imaging scanner. The other technique is magnetic resonance spectroscopic imaging, known as MRSI and recognized as a unique tool to obtain molecule-specific information, enabling the characterization of biochemical properties of tissues.
QSM and MRSI provide complementary information useful for many research and clinical applications, such as the study of brain metabolism, diagnosis and characterization of neurological disorders and assessment of therapeutic efficacy. But currently, they are carried out in separate scans, and both often require long data acquisition times. Conventional QSM methods typically takes five to 10 minutes to cover the whole brain, while MRSI scans can take 30 minutes.
In a study published in October in the journal Magnetic Resonance in Medicine, Zhi-Pei Liang and colleagues at the University of Illinois Urbana-Champaign demonstrated the feasibility of simultaneously mapping brain metabolites and tissue magnetic susceptibility from a single scan. They used a recently developed MRSI technique known as SPICE (SPectroscopic Imaging by exploiting spatiospectral CorrElation), taking advantage of the fact that tissue susceptibility information is naturally encoded in signals from an MRSI scan under certain conditions. SPICE has been used mainly for metabolic imaging, but the authors extended its data acquisition and data processing steps to make it more suitable for simultaneous QSM and metabolic imaging.
The researchers obtained high-resolution metabolite and tissue susceptibility maps of the brain from a single seven-minute scan. According to the authors, this new imaging capability may prove useful for a wide range of applications, including the study of brain metabolism and neurodegenerative diseases.